Originally Posted by estasnyc

You misunderstood why I was asking that question. That was probably because I misunderstood how the Looney Bin cage is to be mounted.

Here's a picture of the entire Looney Bin in which I labelled the visible holes from 1 to 4.



I was under the impression that you might have one of two choices for mounting the Looney Bin, using either holes 1 and 3 or holes 2 and 4.

I had doubts that you might get back to me on this so I considered how I might figure this out having only this photo.

I then realized that everything should be in proportion. What I worked out is that the distance between holes 1 and 4 is twelve times the width of the holes.

But the holes need to accommodate an M5 screw and so would be slightly larger than 5mm. My best guess would be 5.3mm

12 x 5.3mm = 63.6mm which is very close to 2.5" which is the distance between cage mounts.

There is no alternative mounting. My bad.

And this is one way to overthink about mounting a bottle cage under the downtube.